Heater



FIG. 1 is a front perspective view of a heater;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a front side view thereof;

FIG. 4 is a back side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a left side view thereof;

FIG. 7 is a top view thereof;

FIG. 8 is a bottom view thereof;

FIG. 9 is an enlarged view of detail 9 of FIG. 1; and,

FIG. 10 is an enlarged view of detail 10 of FIG. 1.

The broken lines shown in the drawings depict portions of the heater that form no part of the claimed design. 

CLAIM The ornamental design for a heater, as shown and described. 